1. Technical Field
The present invention relates to a thiadiazole, a light-emitting element, a light-emitting apparatus, an authentication apparatus, and an electronic device.
2. Related Art
Organic electroluminescent elements (organic EL elements) are light-emitting elements composed of an anode, a cathode, and at least one organic light-emitting layer disposed between them. Upon the application of an electric field between the anode and the cathode, holes in the anode and electrons in the cathode are injected into the light-emitting layer or layers and generate excitons. When these excitons disappear (i.e., when the electrons and the holes recombine), energy is released, at least in part in the form of fluorescence or phosphorescence.
A known example of such a light-emitting element is one that emits a long-wavelength light of more than 700 nm (e.g., see JP-A-2000-091073 and JP-A-2001-110570).
In a light-emitting element of those types that are described in these patent publications, for example, the light-emitting layer or layers are doped with a compound that contains both electron-donating and electron-withdrawing functional groups, namely amine and a nitrile group, in the molecule. As a result, the light-emitting element can emit light with such a long wavelength. However, it has been impossible to provide such near-infrared-emitting elements with high efficiency and long life.
A light-emitting element that is planar, that can emit near-infrared light, and that is of high efficiency and long life are can be used as, for example, a light source for biometric authentication, in which individuals are verified on the basis of their biological traits, such as vein patterns or fingerprints. Light-emitting elements satisfying these requirements are therefore in demand.